Biodegradable Ecoflex encapsulated bacterial cellulose/polypyrrole strain sensor detects motion with high sensitivity, flexibility and scalability.

• Biodegradable bacterial Polypyrrole strain sensor encapsulated with EcoFlex. • In-situ fermentation shows uniform nanofiller dispersion and 3D conductive networks. • Crack-based strain sensing has a working range of 0.05–90% maximal strain. • ΔR/R 0 readings are consistent under different loading rates and strain ranges. • Strain sensor accurately detects minute pulses, applicable to monitor vital signs. Microbial production of biopolymers are non-standard materials in wearable resistive-strain sensors, despite established and desirable scale-up, rheological, ecological and economical properties. In this study, we report a biodegradable bacterial cellulose (BC) crack-based strain sensor prepared by in-situ fermentation with polypyrrole (PPy) and encapsulation with Ecoflex (EF) for human-interactive sensing. In-situ microbial fermentation method not only optimizes the distribution state of PPy but also constructs the three-dimensional conductive network, which contributing to the formation of crack-based sensing mechanism. The as-prepared BC/Ppy@EF strain sensor exhibits high sensitivity (gauge factor of 3.21–4.86), large strain ranges (up to 90% strain), ultralow strain detection limit (0.05%) and remarkable long-term stability without any distinct decline in sensitivity after a constant applied stretching of 90% for 1000 cycles. The strain sensor accurately detected a full range of body motions, including subtle vital signs like pulse, respiration and vocalizations, and was successfully integrated into textiles for human–computer interactions. Consequently, this study provides empirical value for the bio-fabrication and all-green construction design of wearable devices, as well as the development of human–computer interaction. [ABSTRACT FROM AUTHOR]